Olefin compounds, such as ethylene, propylene, butylene and amylene, can be formed from pyrolytic cracking of light petrochemicals. During the cracking process, secondary reactions may also occur producing carbonyl compounds, such as aldehydes and ketones. As a result, the cracked hydrocarbon product stream can also contain significant quantities of aldehydes and ketones.
The cracked hydrocarbon product stream is cooled to remove most of the heavier hydrocarbons, compressed and then treated with a basic wash (pH>7) to remove contaminating acidic compounds, such as hydrogen sulfide and carbon dioxide. When the hydrocarbon stream is passed through the basic wash, the carbonyl compounds, particularly aldehydes, will undergo polymerization in the presence of a base to form condensation polymers known as aldol polymers or red oil. Aldol polymers are essentially insoluble in the basic wash and the hydrocarbon media and deposit on the internal surfaces of process equipment. These deposits can restrict flow through the equipment, which causes the pressure drop to increase across the treating vessel, resulting in a loss of capacity and increased operating costs. If left untreated, the deposition from the fouling components can result in the premature shutdown of a cracking operation.
Although carbonyl scavengers and dispersants are available for removing or inhibiting aldol formation, it would be desirable to have an improved and more economical process for inhibiting the formation of fouling materials and minimizing the deposition of fouling compounds during hydrocarbon processing.